The exemplary embodiment relates to image processing, image presentation, photofinishing, and related arts. It finds particular application in connection with modeling of the chromatic content of a chromatic object, such as an image, and will be described with particular reference thereto.
Chromatic objects, such as images and color palettes, include chromatic content in the form of a set of colors, such as pixels in the case of images and color swatches in the case of color palettes. There are many applications where it is desirable to model the chromatic content of the object, for example, for color transfer from one object to another, for color-based object retrieval, and color-based object classification. In the case of images, for example, the image may include a large number of pixels. It is desirable to generate a representation of the colors of these pixels which can reduce memory storage and retrieval time, but which also serves as a meaningful representation of the actual chromatic content of the object.
Conventionally, there are many methods for modeling images. A traditional approach is to assume that the pixel values in a given color space, such as RGB, Lab, XYZ, or the like, have been generated by a probabilistic model. The model can be discrete or continuous. In the discrete case, an image can be described by a color histogram in which each pixel is quantized, i.e., is assigned to a discrete bin. In the continuous case, the image is modeled by a mixture model, which is generally a Gaussian mixture model (GMM) comprising a weighted set of Gaussian functions. One problem which arises with both these methods is in setting the complexity of the model (the number of bins in the case of the discrete model or the number of Gaussian functions in the continuous model). Since images and color palettes can have widely differing color distributions, there may not be a good complexity setting which fits all of the objects well. In the case of color transfer, for example, the number of Gaussian functions selected can result in artifacts, which results in the color transferred image appearing unnatural.
There remains a need for a system and method which allows the complexity of a model to be set automatically.